Amp Question for 5-stringers...

Ok, What determins if an amp can handle the lo-B frequencies of a 5-string? Is it the power head wattage? The Amp design itself? The speaker wattage and/or frequency range??
I have an older Peavy TNT 160 watt bass AMP I use for practise, and the clip light keeps on flashing, and it sounds distorted even when at lo to med volumes. If I upgrade the 15" speaker will it help? (The TNT is fine with a 4-string).
I'm kinda new at the 5-string (which is an active Jazz). This bass does sound ok with my full setup Carvin/svp-pro / Hartke cabs.

At 160 watts, are you turning the amp up pretty loud when you play? My guess is "probably", that's not a whole lot of power for bass. Especially for the low B, the lower frequencies suck more juice out of the power supply and generally make the amp work harder. I don't think that just replacing the speaker is going to do the trick for you. While the speaker may be "contributing" to the distortion, chances are that most of what you're hearing is coming from the amp.

If you're looking for a cleaner sound with more headroom, the first option to consider would be a higher power amp. Bass dynamics can be pretty extreme, and so a clean undistorted low B sound at high volumes can raise a signal peak of maybe five or six times your average power (or more). If your amp is already pretty much maxxed out at "average" playing volume, then the B peaks will only come through as distortion. For cleanliness at high volumes, you need "headroom", meaning that if your average playing volume is a hundred watts, and you hit a loud low B, you'll get a peak of maybe 5-600 watts. If you're expecting your amp to handle that "cleanly", you should be looking at a 5-600 watt amp.

That's why bass players love 1200 watt amps like the Walter Woods, it's not that they crank it that loud all the time, it's mainly for "headroom". An amp like that will deliver a clean low B at ear-splitting volume, loud enough to blow out most speakers, and plenty loud for just about any venue.

Now, I'm assuming "solid state", 'cause tube amps are different. With tube amps, that distortion can actually be "pleasing" (at least it doesn't sound quite as bad as clipping on a solid state amp). But with solid state amps, it sounds horrible, it's a nasty sound that's best to avoid.

If a new amp is too expensive, you might think about sound reinforcement. Does your amp have a "line out"? (If not, you can build one that you can clip onto your speaker terminals for about five bucks). You can take the line out and plug it into a PA, or into some other amp, to get more power. If you do that, you can turn the preamp volume on your Peavey down (until you don't get anymore distortion and your clip LED doesn't light anymore), and then turn your power amps up, and that should solve the problem.